Some rumors are too big not to repeat: it’s been reported that Microsoft is talking to Yahoo about a possible acquisition, to better compete with Google.

Granted, the original source is The New York Post, but the markets are taking it seriously, and investors are sending Yahoo’s stock soaring. The Post says the purchase price could be on the order of $50 billion.

Microsoft currently trails both Yahoo and Google in the lucrative and growing business of Web search and, by extension, online advertising.

Earlier this week, Yahoo said it would buy 80 percent of advertising exchange Right Media for $680 million, increasing its stake in that company to full control.